This invention relates to opto-semiconductor devices or in particular to a technique effectively applicable to the fabrication of a laser diode (LD) of a ridge structure.
A semiconductor laser (LD) as an opto-semiconductor element is widely used as a light source of an optical communication system or an information processing system. A visible light semiconductor laser is used as a light source of an information processing system such as a document file system as well as CD, DVD device, laser printer, POS and bar code reader.
The semiconductor laser element (opto-semiconductor element) has such a structure that a multiplicity of semiconductor layers (multiple growth layers) are formed by epitaxial growth on a first surface of a semiconductor substrate. An active layer is formed as a middle layer of the multiple growth layers. One of the layer groups sandwiching the active layer constitutes a semiconductor layer group of a first conduction type and the other layer group constitutes a semiconductor layer group of a second conduction type thereby to form a pn junction. Also, in order to form a resonator (optical waveguide) for laser oscillation, various structures including a thin electrode and a ridge structure are employed. In the semiconductor laser element, a structure is employed in which an anode (positive electrode) and a cathode (negative electrode) are arranged on one surface or separately on obverse and reverse surfaces thereof, respectively.
In the case where the semiconductor laser element (semiconductor laser chip) is fixed on a submount arranged in a package, AuSn or the like solder is used as a fixing means.